1994 D90 Occasionally Wont Start

[OldBay]

I am new to the world of defender ownership. I purchased a 1994 D90 NAS over the summer. It is occasionally hard (impossible) to start. Cranks and Cranks with no noticeable combustion. Sometimes I try again 8 hours later and it fires right up.

All ignition system components were replace shortly after I purchased the defender by a legitimate shop.

When the defender does start (which it generally does) the idle is a little sloppy, often dropping down to 300 rpm before usually bouncing back up to 900, or occasionally stalling. Once the coolant temp comes up Idle seems ok. If I run the engine cold and I ask for power I sometimes feel like the engine is being starved for something, either fuel or air. Once engine is up to operating temp all seems fine.

I hadn't used the defender for 2 weeks in July. When I tried to fire it up, I couldn't get it started. Had the defender towed to the shop. They pulled the plugs and said she was getting plenty of fuel and spark. Pulled all of the ignition wires off, put them all back on and it worked fine.

I've been poking around online and its seems that a problem with the Idle Air Control Motor may cause similar symptoms. I ordered a new Idle Air Control Motor from Rovers North today. I'm going to pull the current IAC this evening to see if it filthy.

Anything else to check?

 

[evilfij]

Replace silver relays.

When it did not start, did you smell raw fuel? If not, silver relays. Did you hear the fuel pump run? If not, silver relays.

A bad IAC, if you give it some throttle while cranking, it will start.

I would also check the intake hose for cracks. Frankly, if it is the old cloth style, replace it regardless.

Check to make sure the ECU is not getting wet. It is in the passenger side footwell on a 94.

Check ohms on coolant temp sensor. Make sure it’s not bad.

Same for TPS.

Finally, replace the ignition module. There used to be a relocation kit, it may still be available.

Not saying any of these are your issue, but they are SO common as to be needed checks/repairs/spares to keep in the truck (I carry a spare ECU too, but they are now hard to find).

No starts are 70% silver relays in my experience, followed by ignition module or has connection at the coil. The sensor will mess with stuff and the busted intake hose will too, but not often a no start. You can also disconnect the MAF and try starting which I think takes all that stuff out of the system.

 

[OldBay]

Thanks for this. Ignition module was moved and replaced and Coolant temp sensor was replaced during service right after I purchased the defender. Once I figure out what silver relays are, I'll replace them. Thanks again.

 

[D901560]

The silver relays are for the fuel pump and EFI system. They are located near the ECU and size wise are approximate 1 inch cubes. The newer ones I have bought recently are not silver so yours may not be either if they have been replaced. I also I keep a spare in the truck. If your 94 has A/C then the relays may be behind the the A/C in the passenger footwell.

 

[evilfij]

And while I am giving what should be universal Land Rover defender advice, buy yourself #2 and #3 pozidriv screwdrivers and keep them in the truck. All the original screws are not Philips, they are pozidriv. Makes getting them out SO much easier and vastly less likely to strip rusty screws.

Edit: not sure why bolded. I suck at the internet. NAS defenders are the height of my technical knowledge. ;-)

 

[rocky]

I had a similar frustration. Drive a distance, park and the following day nothing. Most annoyingly it did this at Winter Romp once and dang it.....

Ultimately we put a scope on the ECU, having exhausted everything else....and it wasn't happy. Opened it up and rampant evidence of water damage and burn marks. Replacing it worked to solve the starting problem.

 

[Surveyor]

I had a similar issue. The fuel pump would not engage. Sometimes taking up to 6 turns of the key other times engaging the first try. Totally random. Happened a few years ago the shop went through the system replacing the relays and fuel pump. This time they found a bad roll over switch and replaced it. Haven't had a problem for the last two weeks.
Keeping my fingers crossed.

 

[evilfij]

I had a similar issue. The fuel pump would not engage. Sometimes taking up to 6 turns of the key other times engaging the first try. Totally random. Happened a few years ago the shop went through the system replacing the relays and fuel pump. This time they found a bad roll over switch and replaced it. Haven't had a problem for the last two weeks.
Keeping my fingers crossed.

I have seen this on JimC’s truck.